Friday, June 10, 2016

18TB with ext4 filesystem



I have the server with 4 disks 6TB each. At start disks were configured as RAID 10 and I had 11TB partition with ex4 filesystem on it. I grew up RAID from level 10 to 5 and now it’s 17.9TB. After reconfiguring RAID I used resize2fs for resize partition, but with ext4 32 bit it give me only 16TB available space. How can I use more than 16TB?



This is parted print information:



GNU Parted 3.2


Using /dev/md3

Welcome to GNU Parted! Type 'help' to view a list of commands.

(parted) p

Model: Linux Software RAID Array (md)

Disk /dev/md3: 17.9TB


Sector size (logical/physical): 512B/4096B

Partition Table: loop

Disk Flags:

Number Start End Size File system Flags

1 0.00B 17.9TB 17.9TB ext4



This is available space:



df -h

Filesystem Size

/dev/md3 16T



Maybe I can create second partition?



Thanks.


Answer



It is a limitation of x32 ext4. Check this link as a possible workaround. Don't use RAID-5 for spindle drives especially for 6TB drives. Just imagine the time of rebuilding the RAID array in case if your disk will fail and very poor write performance.


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